Blue Posted September 21, 2017 Share Posted September 21, 2017 (edited) Why are no.3 & no.4 downpipes not getting as hot as the other 2? I removed plug no.4 & turned engine over, the plug sparked. I then swapped it with no.1 plug but still cylinders 3 & 4 downpipes are much cooler. Edited September 21, 2017 by Blue Quote Link to comment
Gixer1460 Posted September 21, 2017 Share Posted September 21, 2017 If its a pair of un-matched cylinders, its unlikely to be electrical - unless both coils, plug leads, plug caps or spark plugs are duff at same time! Which leaves carbs - everybody's favorite subject - i'd start with a strip and see whats blocked - pilots. idle air, float valve would be candidates! Quote Link to comment
Blue Posted September 21, 2017 Author Share Posted September 21, 2017 Carbs have been off recently because I discovered I had dynojet tubes & factorypro needles, so I bought a set of standard tubes & fitted 147.5 jets (I think) Quote Link to comment
colinworth79 Posted September 21, 2017 Share Posted September 21, 2017 if its a gsxr then there is 2 petrol pipes maybe one is blocked. As above start with cleaning the carbs and then check there balanced . Quote Link to comment
Blue Posted September 21, 2017 Author Share Posted September 21, 2017 (edited) I was gonna go to a dyno this weekend, I wasn't sure if I'd balanced them so I checked that's when I noticed it wasn't running right Edited September 21, 2017 by Blue Quote Link to comment
Blue Posted September 21, 2017 Author Share Posted September 21, 2017 Can I rule out electrical even though I've just rewired the bike ? Quote Link to comment
Gixer1460 Posted September 21, 2017 Share Posted September 21, 2017 2 hours ago, Blue said: Can I rule out electrical even though I've just rewired the bike ? If 1 and 2 are running then both coils are working and so 3 and 4 will be getting sparks (or see my post above). If you have sparks and you have air and it still ain't running then it ain't getting the last bit - fuel ! Quote Link to comment
Oilyspanner Posted September 22, 2017 Share Posted September 22, 2017 (edited) Some very good advice given - has to be intake side, could be air leaking in via seals in intake boots/pilot screw seals (often doesn't show when balancing carbs) - or as been suggested, pilot system/float height etc - what colour are the spark plugs on 3 & 4 ? Edited September 22, 2017 by Oilyspanner spark plug condition Quote Link to comment
Blue Posted September 22, 2017 Author Share Posted September 22, 2017 Didn't check 2&3 but no.4 looked untouched after I'd initially cleaned them & no.1 was black Quote Link to comment
Gixer1460 Posted September 22, 2017 Share Posted September 22, 2017 If #1 was black - dry black or wet black or oily black? If dry - then potentially v. rich. If wet - then potentially leaky float valve / v. rich. If oily then could be leaky valve stem seals or rings. Poor electrics / bad sparks could also cause 1 and 2 as well due to poor combustion. Dirty plugs - particularly NGK's - don't successfully clean up...... so best replace to eliminate that as a symptom! Quote Link to comment
Blue Posted September 26, 2017 Author Share Posted September 26, 2017 Managed to get some time for n this today, pilot jets were blocked or restricted & I've lowered the needle due to the fact I have the needle straightening widgets fitted Quote Link to comment
andydrinkell Posted October 10, 2017 Share Posted October 10, 2017 Had a "mate" tell me about the carb problems on these bikes. He then stated, in a very loud voice, that anyone who bought one of these bikes wasn't all there and should be locked up as they weren't exactly firing on all cylinders. This from a guy with an MZ..... Treated it with the contempt it deserved, lol. Quote Link to comment
Beevis Posted October 12, 2017 Share Posted October 12, 2017 Have you fixed it? from recent experience of a similar problem I found pilot jets blocked and a low fuel level in the tank caused 1 and 2 to stop working before 3 and 4, no idea why. Quote Link to comment
Blue Posted October 12, 2017 Author Share Posted October 12, 2017 Yes Beevis, as mentioned above, some pilots were blocked & some restricted 1 Quote Link to comment
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